1. Field of the Invention
The present invention relates to an interfacial surface generator or ISG, and more particularly to an apparatus for dividing a composite polymer stream into sub-streams, followed by reshaping, repositioning, and recombining the sub-streams to produce a multi-layer laminate.
2. Description of the Related Art
U.S. Pat. No. 5,094,793 discloses an ISG utilizing a series of plates that are stacked in the Z-direction of an XYZ coordinate system, each plate having closed conduits machined therethrough in the Z direction. The first plate divides a composite polymer stream into a plurality of sub-streams arranged side-by-side in the X direction and repositions the sub-streams one over another in the Y direction; the second plate expands the sub-streams in the X direction; and the third plate compresses the sub-streams in the Y direction and combines them back into a stream having the same cross-section as the original stream. The plates do not offer any possibility of being useful for re-configuring a composite stream received from an opposite direction. Further, the change in cross-sectional areas of the conduits in the second and third plates introduces shear stresses in sub-streams that can be a disadvantage under some rheological conditions. In order to create the square and rectangular profiles of the conduits through the plates, manufacturing requires electron beam machining, which can be time consuming and expensive.
U.S. Pat. No. 5,628,950 discloses another ISG utilizing a stacked plate arrangement, wherein each plate consists of a flat blade sandwiched between a pair of housing sections, each housing section having an open conduit that is closed by the blade. The first plate divides a composite polymer stream into side-by-side sub-streams, and shifts the sub-streams in the Y direction. The second plate repositions the sub-streams in the X direction so that they are one over another. The third plate widens and flattens the sub-streams so that they can be recombined. Because the cross-sectional areas of the sub-streams remain constant as they pass through the plates, the shear stresses in the sub-streams is kept to a minimum. Further, the open conduits in the housing sections can be achieved with traditional machining methods. A major disadvantage is that so many pieces are required, including three different blades and six housing sections with three different conduit profiles.
U.S. Pat. No. 3,239,197 discloses an ISG utilizing a series of baffles nested in a pair of opposing channels formed in respective housing sections. Each baffle is provided with dividing members and deflecting surfaces that cooperate with the channel walls to form closed conduits that first divide a composite polymer stream in the Y direction into two sub-streams, then compress and shift the sub-streams in the X direction, then expand the sub-streams in the Y direction. The next baffle in the channels performs the same operations. Since the cross-sectional areas of the sub-streams are constantly changing, constantly changing flow rates introduce shear stresses that tend to destroy laminarity of the layers and mix the sub-streams. Indeed, the apparatus is designed as a mixer. There is no suggestion that the ISG could be utilized for flow in the opposite direction.